At the world premiere of Martin Scorsese’s new film, Silence, held at the Vatican, Pope Francis joked that its star, Andrew Garfield, deserved to be ordained. It was high praise indeed for the actor formerly best known as The Amazing Spider-Man, this time channelling a Jesuit missionary in 17th-century Japan. Better than an Oscar nomination? Garfield has been hotly tipped. He dodges the question. “I love the pope – he’s a really progressive guy. He’s talking progressively about the LGBTQ community. He’s turning the dial up slowly, by however much he can. He’s doing that ‘slow work of God’ stuff.” Garfield pauses, realising this might sound self-congratulatory. “But I loved the pope before he was even aware of my existence.”

We are sitting in a booth in a Tarantino-esque diner in Los Angeles, hipster tinsel lining the windows. Aptly, Tim Roth strolls past and Garfield mouths, “I fucking love Tim Roth” at me, before making a sign of the cross. Today Garfield is elfin-lank in grey sweater and jeans, unevenly stubbled, with an upwards sweep of hair that looks as if it’s held up by sheer enthusiasm rather than hair gel. His simpatico grin exposes what look like baby teeth; at 33, he could pass for 22.

There are two Garfields: a playful one who swears a lot and worries about “sounding like a pretentious fucker” (let’s call him Andy); and a sincere, serious one, who answers in fully formed thoughts and likes his devotional metaphors (more of an Andrew). The effect is rather like talking to a sweet but potty-mouthed choirboy who, without warning, turns into the impassioned debating team captain.

“Andrew” describes Scorsese’s new film as “a meditation and a prayer”, an experience that is still “reverberating” for him. An immersive preparer, Garfield studied to be a Jesuit priest for a year, practising St Ignatius of Loyola’s prescribed meditations on Christ’s life, visualising every gospel one by one, including his journeyfrom Via Dolorosa to Calvary. He rented a spartan room in New York, and went on a silent Jesuit retreat in Wales.

Garfield with Shinya Tsukamoto in Martin Scorsese’s new film Silence. Photograph: Kerry Brown/Paramount

Garfield’s New York-based coach, Father James Martin, continues to be his spiritual adviser, guiding the actor in his own “very specific relationship with Jesus” – a kind of hipster, leftwing reading of him. “I had no relationship to [Jesus] beforehand,” Garfield says. “He was just the frontman for Christianity.” Before working on the film, he was “pantheist, agnostic, occasionally atheist and a little bit Jewish, but mostly confused”.

I remind him of America’s president-elect waving a Bible on the campaign trail, urging evangelical Christians to see him as the God-appointed candidate, and Garfield almost spits out his runny egg and grits. “It’s all a ruse. How can that not be clear to everybody? When the pope says that Jesus Christ was about building bridges, not building walls. And then Donald Trump bashes the pope – in effect, he bashes Jesus Christ.”

Silence, adapted from the 1966 novel by Shūsaku Endō, had been in development since 1990, and was originally intended as Scorsese’s follow-up to The Last Temptation Of Christ (1988). But the director kept delaying, most recently in favour of The Wolf Of Wall Street. The finished film is the Temptation story cut to the bone and stripped of theological baggage: the tale of two callow Portuguese Jesuit priests, Fathers Rodrigues (Garfield) and Francisco Garrpe (Adam Driver), who travel to Japan on a mission to prove the innocence of their mentor, who is rumoured to have gone over to the brutal Buddhist regime.

People who are certain are terrifying to me

A compelling meditation on personal faith, Silence at times breaks through into masterpiece territory; Rodrigo Prieto’s painterly cinematography turns some chiaroscuro frames into pure Caravaggio. There is a sense of a 74-year-old man staring down the barrel of his own mortality, and Garfield recalls the “devotion” on Scorsese’s face throughout production: “How amazing [it was] to hang out with him when he was figuring all this stuff out.”

They filmed from January 2015 on a minimal budget in Taiwan: an arduous four months during which Garfield slept three hours a night, trekked mountainous terrain, endured typhoons, and fasted enough to lose 40 pounds (he remembers vivid nightly dreams about food). It sounds like the perfect antidote to the commercial juggernaut of The Amazing Spider-Man franchise which, I had read, triggered a crisis in Garfield’s faith in his industry. “I wouldn’t say I had a crisis of faith,” he says, and then qualifies: “I’m always having a crisis of faith, with everything. People who are certain are terrifying to me. That’s how religious wars get started.”

In November 2014, two months before Garfield started shooting Silence, Mel Gibson approached him about a role in Hacksaw Ridge. The film is a mighty-is-the-lamb true story about Seventh Day Adventist Desmond T Doss who, while serving as a military medic, evacuated 75 wounded men from the Battle of Okinawa in 1945 without picking up a weapon.

Gibson’s first film since Apocalypto a decade ago, it is not hard to read Hacksaw Ridge as a two-hour-and-20-minute plea for forgiveness. A conservative Christian, the director was arrested in 2006 for drink-driving and launched into a racist attack on his Jewish arresting officer. He apologised, but it was too late; Hollywood turned its back. “I think everyone can relate to that feeling of exile,” says Garfield, who plays Doss. “That feeling of being misunderstood, not being seen in a deep way. Kind of kept out of the inner circle.”

If Garfield is choosing his words carefully, it is partly because his paternal grandfather, Samuel Garfinkel, was a Jewish émigré to London (although Garfield was brought up in a secular household). “I read the script and I heard Mel was directing it, and I felt excitement about him as a film-maker. But I needed to sit with him to get to know him, as a person, because no one can avoid the news and celebrity gossip. When we met, I got to know the real Mel, the six-years-sober Mel, and I experienced a good soul, a man who has done a lot of work on himself.”

So he thinks Gibson should be shown more compassion? “Alcoholism is a disease. I’ve known alcoholics and I’ve known addicts. And thankfully I have a lot of compassion around that.” Garfield’s friend Heath Ledger died from a prescription drug overdose while they were both shooting Terry Gilliam’s The Imaginarium Of Doctor Parnassus; Garfield also starred opposite the late Philip Seymour Hoffman in Mike Nichols’ Broadway production of Death Of A Salesman in 2012.

For the past four years, Garfield has been largely defined by Spider-Man. He and his co-star (and then girlfriend) Emma Stone were for a time the hot Hollywood power couple; but Garfield’s success followed years of high-calibre work in the UK, from television drama Boy A (2007), in which he played a child killer released back into the world (the role won him a Bafta), to the eerie innocence of his human-donor clone child in Never Let Me Go (2010). He has a knack of upping a film’s emotional ante: Garfield brought the heart and moral compass to David Fincher’s The Social Network (2010), playing Facebook co-founder Eduardo Saverin (a role that won him a Golden Globe nomination).

Born in Los Angeles, Garfield has British and American citizenship. His family moved from his father’s native California, where his parents ran a designer lampshade business, to Epsom in Surrey when he was three. His mother Lynne, who is from Essex, found a job as a nursery schoolteacher and his father as a coach at Guildford swimming club. Garfield went to school in Banstead, where he says he was bullied for being small and slight. He was a natural gymnast, but also an emotional, sensitive soul (“a navel gazer in the extreme”) who liked to watch Michael J Fox films. “I was a monkey child. I was like a clown. My grandmother said, ‘You’re going to go to clown college’ and I was like, ‘OK, that sounds good.’

“I was raised with the idea that the arts were a doss – but the arts are vital,” he continues. “If you see Mark Rylance perform Shakespeare at the Globe, you know it’s a spiritual act. And it’s not reflected in the way the Conservative government is trying to cut funding in England. The [British] government doesn’t value the arts. And the fact that the American president-elect is in a feud with the greatest musical of the last few decades [Hamilton, which Trump denounced on Twitter after the cast were “very rude” to his vice-president-elect] – well, it’s an example of how the arts are treated in both countries.”

He hopes that his and Gibson’s Desmond Doss can reach out from beyond the grave into the liberal bubble, as a positive portrayal of a midwestern man at a time of global condescension towards white, American Christians. (The role has already earned Garfield a Golden Globe nomination.)

Does he think Doss would have voted Trump? “Hell, no! He was treating Japanese soldiers in the middle of a war. He doesn’t see skin colour. He doesn’t see an enemy. He sees humanity. He is the opposite of values that I believe the future president inhabits and symbolises. Trump is a man who is interested only in himself – narcissistic, grandiose and toxic. He’s a tyrant king whom we’ve just given all our power to and applauded for embodying the modern value system of narcissism and self-absorption. He’s the richest man in the graveyard.”

It was a performance in Kes at Manchester’s Royal Exchange theatre in 2004, after graduating from the Central School of Speech and Drama, that set the politically engaged tone of Garfield’s career. Two years later, he was invited to screen-test for Stephen Daldry and the tape found its way to Robert Redford, who cast him in Lions For Lambs (2007) alongside Meryl Streep.

When The Amazing Spider-Man came calling, Garfield endowed the superhero with both an ordinariness and a human complexity. The Guardian described him as “definitive”, but the sequel proved a box-office disappointment. By now, three or four spin-offs were planned, with ever more overpopulated and ludicrous plots. Then, fearing audience superhero ennui, Sony got cold feet.

The publication of a hacked Sony email in May 2015 implied that Garfield, who had spoken openly about his disappointment with the films, was “let go” after failing to turn up to an event in Brazil where Sony boss Kaz Hirai was due to announce The Amazing Spider-Man 3, set for release in July 2017. Garfield cited sickness caused by jetlag, and the studio announced the casting of 19-year-old Tom Holland.

Did Garfield deliberately self-sabotage? “No, I don’t think so.” He laughs. Was there a row with the studio? “What I’ll proudly say is that I didn’t compromise who I was, I was only ever myself. And that might have been difficult for some people.”

People are rewarded with money and fame, and ultimately the correct amount of emptiness for an egocentric life

At the time, he had a little rant about the studio wanting to pluck his eyebrows “just so”. Was that a metaphor or an actual incident? “Both. They wanted to thin them out.” And it profoundly affected him? “Oh no. But I learned so much about what feels good and what doesn’t.”

He says he always saw Spider-Man as a modern myth, and in retrospect might have been overthinking it. “I’d been reading the mythologists Joseph Campbell and James Hillman. And when I took on Spider-Man, I thought, ‘Holy shit! This is exquisite and terrifying and incredible. I have been given the responsibility of reaching my hand out from the big screen and putting it on [young boys’] shoulders. That is a gift for me and a big burden to carry. And I’m so up for it.’

“I thought, if I can infuse all this ancient knowledge and wisdom into [Spider-Man], it could be profoundly affecting for young people in the audience. That was always my intention and what I tried to do.” He laughs. Wasn’t that naive? “Yes, of course! I was 25 and I was naive – not because of that, but because I was naive to the whole process of making one of those big-budget films.”

He seemed to have felt a profound discomfort with participating in celebrity culture, looking mortified on press tours with Stone by his side, desperately trying to loosen her boyfriend up, ribbing him into his “Andy” incarnation. (The two remain close since they split last year, and Garfield is generous about the ex now tipped to win the best actress Oscar for La La Land. “I’m always cheering Emma on, in all ways. I’m one of the millions who is grateful that she exists.”)

Andrew Garfield, left, and Jesse Eisenberg in The Social Network. Photograph: Merrick Morton

That discomfort with fame is still there. “The poison in the water started a long time ago,” Garfield says, “with the birth of Hollywood and Edward Bernays [the American pioneer of public relations], propaganda and PR. We’re all in the same position now, because we all have the ability to self-promote. People are rewarded with money and fame, and ultimately the correct amount of emptiness for an egocentric life. There’s part of me that will always want to shed all that.”

Garfield will start the new year at the National Theatre in London, rehearsing Tony Kushner’s Pulitzer prize-winning Angels In America, in which he’ll play Prior Walter, the HIV-positive New Yorker who receives angelic visitations. He doesn’t own a home, either in the UK or the US, and stores his belongings between his parents’ home in Surrey and a storage depot in New York; he hasn’t really had time to house-hunt. Next up, he will star opposite Claire Foy (The Crown) as Robin Cavendish, a man who was paralysed by polio at 28, in Andy Serkis’s biopic Breathe.

Most of the time, Garfield tells me, he doesn’t really “fit in” with his generation. He doesn’t have a Twitter or Instagram account. He talks about the dehumanising effects of the digital world (in 2010, he appeared in Spike Jonze’s short film I’m Here, about two robots in love).

He recalls the time a seven-year-old boy who recognised him as Spider-Man filmed him playing basketball in New York.

“I was horrible and sweaty. I thought to myself, ‘I’m not very good at basketball, I don’t really want that.’ See? The ego crept in. I started running towards him like I was going to tackle him, just joking around with him. But he’s not moving. He was just looking at the screen, slack-jawed. Until I’m right in front of him. I said, ‘Hello!’ and he pulled the phone down for a second and freaked out. It was so dissociative. I was scared for him. I could have been a really bad dude and I could have hurt him. I mean, go and climb a tree!” •

• Silence is released on 1 January; Hacksaw Ridge is released on 27 January.

This article was amended on 31 December 2016 to correct a detail about an award. Andrew Garfield was nominated for but did not win a Golden Globe award for his performance in The Social Network.